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Understanding the Roof Valley System

November 27, 2017 0 Comments

A roof valley is a system which allows water to be drained from a roof in an efficient, controlled manner.

Australian Homes with Roof ValleysAs the name suggests, they are v-shaped and usually built from galvanised metal to ensure durability and cost-effectiveness. Valleys run alongside the folds in a roof where different aspects come together, protecting homes from any potential leaks or damage caused by the weather.

There are different methods of installation for roof valleys, which are designed to increase the performance or lifespan of this particular part of the roofing.

Most homes will have either woven or laced roof valleys, or common cut valleys. When it comes to looking at the particular type of valley being installed or replaced on a building project, it’s best to consider every home on a case-by-case basis due to average temperatures or levels of rainfall in any one area.

There are certain components of the roof valley that are vital to ensuring stable roof construction no matter what style was chosen. For example, metal flashing can mean the roof valleys last for a far longer time. Flashing is installed on top of the felt paper forming the basis of the roof, and protects the roof from any water seepage. Common materials used for flashing include galvanised metals, galvanised alloys, stainless steel, standard copper or lead-coated copper, all of which are sturdy choices. The material used for valley boards and rafters are also important. A valley rafter is set at a 45° angle from the corners of two adjoining plates, connecting to the roof’s ridge. As such an integral part of the roof’s structure, it’s important that these rafters are also built from sturdy materials.

If badly maintained, a valley roofing can become vulnerable to a whole host of issues. Due to the nature of the metal used to build roof valleys, small rust holes can quickly become a much bigger problem. If ignored, these small holes will gradually get bigger, accompanied by an increasingly serious leak.

There are also a number of other potential issues that can come about with roof valleys, all of which can be avoided through proper maintenance and roof care. For example, something as deceptively trivial as trapped leaves can lead to the corrosion of the metal the valley is constructed from. A larger amount of trapped leaves or other materials can also cause a blockage, and the resultant damming effect can mean serious water damage and a big repair bill for the roof cavity.

Due to the metal most roof valleys are built from, the expansion and contraction of the roof valley in hot or cold weather can also cause cracks and splits to occur, which becomes a serious problem during heavy rainfall.

Most roof valleys will only need replacing after at least a decade, but without proper maintenance, and if problems are left to fester, several years could be taken off the lifespan of the roof valley. This can lead to disgruntled clients – suspecting you, as the builder, did not do your job correctly, and accusing you of cutting corners. Encourage your clients to clean their gutters regularly to look after the roof valley system of their house. Choose the most hard-wearing metal, checking first that it has been tested to ensure it’s perfect for the job.

Filed in: Trade Tips

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